Systems Analysis and Design in a Changing World

Systems Analysis and Design in a Changing World, Fourth Edition 16

16 Learning Objectives u Explain the foundations for the adaptive methodologies to development u List and describe the features of the Unified Process system development methodology u List and describe the features of Agile Modeling u Describe the features of Extreme Programming. u Explain the importance of Model-Driven Architecture on enterprise-level development u Describe frameworks and components, the process by which they are developed, and their impact on system development Systems Analysis and Design in a Changing World, 4 th Edition 2

16 Overview u The IS discipline is dynamic and always changing u More complex system requirements have necessitated a whole new set of tools u IS professionals are also creating a new techniques and methodologies for building systems. l The Unified Process (UP) l Radical, adaptive approaches, including Agile Development, Extreme Programming. l Object frameworks and components to increase productivity and quality Systems Analysis and Design in a Changing World, 4 th Edition 3

16 Software Principles and Practices u Ubiquitous computing: is the current trend in our society l Using computer technology in every aspect of our lives u The effort to develop current solutions is demanding u No single solution or technology can satisfy all needs. u What have you learned so far ? ? u Current trends in modeling and development processes use five important principles o Abstraction, models and modeling, Pattern, Reuse, Methodologies Systems Analysis and Design in a Changing World, 4 th Edition 4

16 Software Principles and Practices (continued) u Abstraction l l u Process of extracting core principles from a set of facts or statement Example: Metamodels describe the characteristics of another model Models and modeling l An abstraction of something in the real world, representing a particular set of properties. l Modeling help us to crystalize our thinking so that we are more precise. l We use model to documents ideas that we need to remember. Systems Analysis and Design in a Changing World, 4 th Edition 5

16 Software Principles and Practices (continued) u Patterns l u Reuse l u Standard solutions to a given problem or templates that can be applied to a problem Building standard solutions and components that can be used over and over again ( to develop graphical user interface for the windows platforms, all developers use standard class libraries of forms, buttons, etc. ) Methodologies l A process—including the rules, guidelines, and techniques—that defines how systems are built and development project are managed. 6

16 Adaptive Approaches to Development u Opposite end of spectrum from predictive approaches (recall Chapter 2) u Allow for uncertainty u Use empirical controls, not predictive controls l Describe processes that are variable and unpredictable l Monitor progress and make corrections on the fly, based on specific situation. Because many software development projects contain a high a mount of uncertainty, an empirical process might be a better choice for them. Systems Analysis and Design in a Changing World, 4 th Edition 7

Adaptive Approaches to Development— Characteristics v u 16 All adaptive methodologies use empirical controls and have their own rules and guidelines, however, they do share a few characteristics: Less emphasis on up-front analysis, design, and documentation u More focus on incremental development u More user involvement in project teams u Reduced detailed planning l Used for near-term work phases only u Tightly control schedules by fitting work into discrete time boxes u More use of small work teams that are self-organizing Systems Analysis and Design in a Changing World, 4 th Edition 8

16 The Unified Process (UP) u Object-oriented system development methodology (system development process) u Offered by Rational/IBM, UP developed by Booch, Rumbaugh, and Jacobson, also, there are behind the success of UML. u UP should be tailored to organizational and project needs u Highly iterative approach to development (life cycle) u Project will be use-case driven and modeled using UML Systems Analysis and Design in a Changing World, 4 th Edition 9

16 The Unified Process Life Cycle u UP life cycle l Includes four phases which consist of iterations l Iterations are “mini-projects” u Inception – develop and refine system vision ( usually completed in one iteration). u Elaboration – define and complete the requirements, design and implementation of the core architecture (involves several iterations). u Construction – continue design and implementation of routine, less risky parts ( involves several iterations) u Transition – move the system into operational mode ( one or more final iterations involve the final user acceptance and beta version) Systems Analysis and Design in a Changing World, 4 th Edition 10

16 The Unified Process Life Cycle (Figure 16 -1) Systems Analysis and Design in a Changing World, 4 th Edition 11

16 UP Phases and Objectives (Figure 16 -2) Systems Analysis and Design in a Changing World, 4 th Edition 12

The UP Disciplines u UP defines disciplines used within each phase u Discipline – set of functionally related development activities u Each iteration includes activities from all disciplines u Activities in each discipline produce artifacts – models, documents, source code, and executable. u Learning CIS/MIS means learning techniques from these disciplines u 16 Six main UP development disciplines l u Business modeling, requirements, design, implementation, testing, and deployment Three additional support disciplines l Project management, configuration and change management, and environment 13

UP Disciplines Used in Varying Amounts in 16 Each Iteration (Figure 16 -3) Systems Analysis and Design in a Changing World, 4 th Edition 14

UP Life Cycle Model 16 Showing Phases, Iterations, and Disciplines (Figure 16 -4) Systems Analysis and Design in a Changing World, 4 th Edition 15

The Agile Development Philosophy and Modeling u 16 Agile Development l A philosophy and set of guidelines for developing software in an unknown, rapidly changing environment u Requires agility – being able to change direction rapidly, even in the middle of a project u Agile Modeling l A philosophy about how to build models, some of which are formal and detailed and others are sketchy and minimal Systems Analysis and Design in a Changing World, 4 th Edition 16

The Agile Development Philosophy and Values u 16 Responding to change over following a plan l An agile project is chaordic which comes from two words chaos and ordered u Individuals and interactions over processes and tools u Working software over comprehensive documentation u Customer collaboration over contract negotiation Systems Analysis and Design in a Changing World, 4 th Edition 17

Adaptive Methodologies Using Agile Modeling (Figure 16 -5) Systems Analysis and Design in a Changing World, 4 th Edition 16 18

16 Agile Modeling Principles u AM is about doing the right kind of modeling at the right level of detail for the right purposes l Use models as a means to an end instead of building models as end deliverables l Does not dictate which models to build or how formal to make those models l Has basic principles to express the attitude that developers should have as they develop software Systems Analysis and Design in a Changing World, 4 th Edition 19

Agile Modeling Principles (Figure 16 -6) Systems Analysis and Design in a Changing World, 4 th Edition 16 20

16 Agile Modeling Practices (Figure 16 -7) Systems Analysis and Design in a Changing World, 4 th Edition 21

16 Extreme Programming (XP) u An adaptive, agile development methodology created in the mid-1990 s u XP is really an attempt to take the best practices of software development and extend them “ to the extreme”. u Takes proven industry best practices and focuses on them intensely u Combines those best practices (in their intense form) in a new way to produce a result that is greater than the sum of the parts Systems Analysis and Design in a Changing World, 4 th Edition 22

16 XP Core Values u Communication l u Simplicity l u In designing and implementing solutions. Feedback l u In open, frequent verbal discussions (One of the major causes of project failure has been a lack of open communications). On functionality and requirements ( from users), designs, and code ( from other developers) Courage l In facing choices such as throwing away bad code or standing up to a too-tight schedule Systems Analysis and Design in a Changing World, 4 th Edition 23

Some XP Practices u u 16 Planning l Users develop a set of stories to describe what the system needs to do. l Involves two aspects: business issues (decided by the user and client) and technical issues( decided by the development team) Testing l Tests are written before solutions are implemented (unit and acceptance testing). Pair programming l Two programmers work together on designing, coding, and testing Simple designs l It is one that accomplishes the desired result with a few classes and methods as possible without duplicate code 24

16 Some XP Practices (continued) u Refactoring l u Owning the code collectively l u Anyone can modify any piece of code ( everyone is responsible for the code). Continuous integration l u Improving code without changing what it does ( before and after adding any new functions, XP programmers review the code to see whethere a simpler design or methods of achieving the same results. Small pieces of code which passed the unit test are integrated into the system daily or more often System metaphor l Guides members towards a vision of the system Systems Analysis and Design in a Changing World, 4 th Edition 25

16 Some XP Practices (continued) u On-site customer l u Small releases l u Produce small and frequent releases to user/customer Forty-hour work week l u Intensive user/customer interaction required Project should be managed to avoid burnout Coding standards l Follow coding standards to ensure flexibility Systems Analysis and Design in a Changing World, 4 th Edition 26

16 XP Core Values and Practices (Figure 16 -8) Systems Analysis and Design in a Changing World, 4 th Edition 27

16 XP Project Activities u System-level activities l l u Occur once during each development project Involve creating user stories to planning releases Release-level activities l l u Cycle multiple times – once for each release Are developed and tested in a period of no more than a few weeks or months Iteration-level activities l Code and test a specific functional subset in a few days or weeks Systems Analysis and Design in a Changing World, 4 th Edition 28

16 XP Development Approach (Figure 16 -9) Systems Analysis and Design in a Changing World, 4 th Edition 29

Project Management and Adaptive Methodologies 16 u How project management changes for adaptive projects? u Project time management l l u Smaller scope and focused on each iteration Realistic work schedules Project scope management l Users and clients are responsible for the scope l Scope control consists of controlling the number of iterations. ---- Note ( Time and scope are always interdependent) u Project cost management l More difficult to predict because the complete project schedules is unknown 30

Project Management and Adaptive Methodologies (continued) u 16 Project communication management l l u Users are heavily involved in all aspects of the project. Critical because of open verbal communication and collaborative work Project quality management l Continual testing and refactoring must be scheduled ü ü u Testing is conducted throughout the project. Time is allocated to refactor the system as it is built, so the resulting system is simple and solid. Project risk management l High-risk aspects addressed in early iterations, as a result, the project team and client found out any obstacle that could seriously failed the project. 31

Project Management and Adaptive Methodologies (continued) u Project human resource management l u 16 Teams organize themselves for each iteration, so project managers are less tempted to take control in adaptive approach. Project procurement management l l Verifying quality of components l Ø Integrating purchased elements into the overall project Satisfying contractual commitments The adaptive and agile concepts that were just discussed focus on individual project within an organization. Systems Analysis and Design in a Changing World, 4 th Edition 32

16 Object Frameworks u A set of classes that are designed to be reused in a variety of programs u The classes within an object framework are called foundation classes l Can be organized into one or more inheritance hierarchies l Application-specific classes can be derived from existing foundation classes l Programmers then add or modify class attributes and methods to adopt a “generic” foundation class to the requirements of a specific application. Systems Analysis and Design in a Changing World, 4 th Edition 33

16 Object Framework Types u User-interface classes l u Generic data structure classes l u Linked lists, binary trees, and so on, and related processing operations Relational database interface classes l u Commonly used objects within a GUI ( windows, menus, toolbars, etc. ) Classes that allow OO to create database tables, add data to a table, query data content of one or more table Classes specific to an application area l For use in a specific industry or application type ( banking, shipping, inventory, etc. ) 34

16 Impact on Design and Implementation v Developers need to consider several issues to determine whether to use object frameworks. u Frameworks must be chosen early in the project u Systems design must conform to specific assumptions about application program structure and operation that the framework imposes u Design and development personnel must be trained to use a framework effectively u Multiple frameworks might be required, necessitating early compatibility and integration testing Systems Analysis and Design in a Changing World, 4 th Edition 35

16 Components u Software modules that are fully assembled and ready to use l u Have well-defined interfaces to connect them to clients or other components l u Reusable packages of executable code Public interfaces and encapsulated implementation Standardized and interchangeable software parts l They differ from objects or classes because they are binary(executable program) , not symbolic ( source code). l Think about grammar checking function l Updating a single component does not require relinking, recompiling, and redistributing an entire application 36

16 Component Standards and Infrastructure u Interoperability of components requires standards to be developed and readily available ( consider the video display of a typical IBM-compatible personal computer) u Components might also require standard support infrastructure l Software components have more flexibility when they can rely on standard infrastructure services to find other components u Networking standards are required for components in different locations u To address these issues, some organization have developed and continue to modify standards for component development and reuse. Systems Analysis and Design in a Changing World, 4 th Edition 37

16 CORBA and COM+ u CORBA (Common Object Request Broker Architecture) is a standard for software component connection and interaction developed by the OMG l l u An object request broker (ORB) provides component directory and communication services The Internet Inter-ORB Protocol (IIOP) is used to communicate among objects and ORBs Component Object Model Plus (COM+) is a standard for software component connection and interaction developed by Microsoft. Systems Analysis and Design in a Changing World, 4 th Edition 38

16 Enterprise Java. Beans u Java is an OO programming language developed by sun microsystems. u Part of the Java programming language’s extensive object framework (JDK, java development kit) which includes classes for GUIs, database manipulation and internetworking. u A Java. Bean can execute on a server and communicate with clients and other components using CORBA l u A Java. Bean implements the required component methods and follows the required naming conventions of the Java. Bean standard Platform independent Systems Analysis and Design in a Changing World, 4 th Edition 39

16 Components and the Development Life Cycle u Component purchase and reuse is a viable approach to speeding completion of a system. Two development scenarios involve components: l Purchased components can form all or part of a newly developed or re-implemented system l Components can be designed in-house and deployed in a newly developed or re-implemented system Systems Analysis and Design in a Changing World, 4 th Edition 40

Using Purchased Components— Implications 16 u Standards and support software of purchased components must become part of the technical requirements definition u A component’s technical support requirements restrict the options considered during software architectural design u Hardware and system software that provide component services must be acquired, installed and configured before testing begins. u The components and their support infrastructure must be maintained after system development. Systems Analysis and Design in a Changing World, 4 th Edition 41

16 Monitoring System Performance v Steps developers should take to ensure adequate performance include the following: u Examine component-based designs to estimate network traffic patterns and demands on computer hardware u Examine existing server capacity and network infrastructure to determine their ability to accommodate communication among components u Upgrade network and server capacity prior to development and testing Systems Analysis and Design in a Changing World, 4 th Edition 42

16 Monitoring System Performance (continued) u Test system performance during development and make any necessary adjustments u Continuously monitor system performance after deployment to detect emerging problems u Redeploy components, upgrade server capacity, and upgrade network capacity to reflect changing conditions Systems Analysis and Design in a Changing World, 4 th Edition 43

16 Services u New method of software reuse enabled by Internet— external services identified and used for applications u Called Web services and service-oriented architecture (SOA) u Microsoft. NET is service standard based on SOAP u Java 2 Web Services (J 2 WS) is service standard for services in Java Systems Analysis and Design in a Changing World, 4 th Edition 44

Component Communication Using SOAP 16 (Figure 16 -14) Systems Analysis and Design in a Changing World, 4 th Edition 45

16 Summary u Adaptive development methodologies l Unified Process (UP) l Agile Modeling and Agile Development u Flexibility l in an unpredictable business world Extreme Programming (XP) u Tests are written first; programmers work in pairs Systems Analysis and Design in a Changing World, 4 th Edition 46

16 Summary (continued) u Software reuse is a fundamental approach to rapid development l Object frameworks provide a means of reusing existing software through inheritance l Components are units of reusable executable code that behave as distributed objects Systems Analysis and Design in a Changing World, 4 th Edition 47